FBI: Pressure cooker bomb components found in Tsarnaev's family home

Fireworks are pictured in this undated handout evidence photo provided by the U.S. Attorney's Office in Boston, Massachusetts on March 25, 2015. U.S. Attorney's Office/Handout/Reuters FBI agents told jurors in the Boston Marathon trial that nails, BBs, pressure cooker parts and other items similar to those used in two pressure-cooker bombs that exploded near the marathon's finish line were found in Dzokhar Tsarnaev's family apartment in Cambridge.

The parts and others purchased by Tsarnaev's brother were found during a search four days after the April 15, 2013 terror attack, which killed three people and injured more than 260 others.

Tsarnaev's lawyers have admitted that he and his older brother, Tamerlan, planted and detonated the bombs. But they say Tamerlan Tsarnaev was the mastermind of the attack.

Tsarnaev's attorneys contend that he had not been living in the apartment since he enrolled at the University of Massachusetts-Dartmouth more than a year before the bombings, so most of what was found there did not belong to him.

Tamerlan, 26, died days after the bombing when he was wounded during a gun battle with police and run over by Dzhokhar as he escaped. Dzhokhar, then 19, was found more than 18 hours later, hiding in a boat parked in a yard in Watertown.

A large fragment of a homemade pressure-cooker bomb that accused Boston Marathon bomber Dzhokhar Tsarnaev is charged with throwing at police officers during a gunfight in Watertown, Massachusetts, on April 19, 2015, is seen embedded in the side of a Honda Civic (C) that was parked near the site of the disturbance, in a handout image entered as evidence during his trial in Boston March 19, 2015. U.S. Attorney's Office/Handout/Reuters The brothers —ethnic Chechens — had lived in the former Soviet republic of Kyrgyzstan and the volatile Dagestan region of Russia before moving to Cambridge with their parents and two sisters about a decade before the bombings.

FBI Special Agent Christopher Derks identified various items belonging to Tsarnaev in the apartment, including his certificate of naturalization showing he had become a U.S. citizen.

He also said agents found a book with two sheets of loose-leaf paper inside with handwritten notes, including the name Tarek Mehanna, a Sudbury man who was convicted of conspiring to help al-Qaida, and a reference to Anwar al-Awlaki, an America-born Muslim cleric and al-Qaida propagandist who was killed in a U.S. drone strike in Yemen in 2011. Derks did not say whose handwriting it was.

A large fragment of a homemade pressure-cooker bomb that accused Boston Marathon bomber Dzhokhar Tsarnaev is charged with throwing at police officers during a gunfight in Watertown, Massachusetts, on April 19, 2015. U.S. Attorney's Office/Handout/Reuters FBI agents told the jury that Tamerlan bought remote-controlled model cars and a transmitter and receiver, and boxes of BBs in the months before the attack.

Prosecutors said previously that the remote-control detonators for the bombs used in the marathon were made from model car parts.